When Hyder is initially remembering his son in his thoughts, the voice we hear (of Hyder's son) is that of a young man. When later remembering him, the voice of Hyder's son is that of Ed Lauter.
While Hyder Rudge is talking to John Boy about his son, he begins to rub the headlight of the car. In the reflection, there's a vehicle and crew members visible in the background.
Elizabeth asks John-Boy if chickens can talk; it's wildly inconsistent that a 7-year-old girl raised in rural Virginia, surrounded by farm animals, wouldn't know that animals can't talk.